نتایج جستجو برای: magnetic matter
تعداد نتایج: 540637 فیلتر نتایج به سال:
A global analysis of the solar neutrino data from all solar neutrino experiments combined with the KamLAND data is presented assuming that the solar neutrino deficit is due to the matter-enhanced spin-flavor precession effect. We used two types of magnetic field profiles throughout the entire Sun: Wood-Saxon shape and the Gaussian shape. We showed that for Dirac neutrinos, the allowed regions a...
Tractography algorithms provide us with the ability to non-invasively reconstruct fiber pathways in the white matter (WM) by exploiting the directional information described with diffusion magnetic resonance. These methods could be divided into two major classes, local and global. Local methods reconstruct each fiber tract iteratively by considering only directional information at the voxel lev...
Diffusion magnetic resonance imaging (dMRI) is a compelling tool for investigating the structure and geometry of brain tissue based on indirect measurement of the diffusion anisotropy of water. Recent developments in global top-down tractogram optimizations enable the estimation of streamline weights, which characterize the connection between gray matter areas. In this work, the intra-axonal cr...
Magnetic susceptibility is one of the most important tools for monitoring the sediment composition during environmental studies. In this research, in order to reconstruct the Caspian Sea level changes, magnetic susceptibility variations were used during the studies of 5 sedimentary cores (K1, K3, K5, K7, N1), collected from bottom sediments of Gorgan Bay. Samples were analyzed for grain size, t...
PURPOSE In multiple sclerosis (MS), a juxtacortical lesion at the border between the gray matter (GM) and subcortical white matter (WM) may often involve the GM. A recently developed, phase-weighted magnetic resonance imaging (MRI) technique "phase difference enhanced imaging (PADRE)" can delineate the GM and WM clearly due to the difference in myelin concentration. We evaluated whether PADRE i...
White and grey matter lesions are the most prevalent type of injury observable in the Magnetic Resonance Images (MRIs) of children with cerebral palsy (CP). Previous studies investigating the impact of lesions in children with CP have been qualitative, limited by the lack of automated segmentation approaches in this setting. As a result, the quantitative relationship between lesion burden has y...
We derive the form of the magnetic stress tensor in a completely general, stationary magnetic medium, with an arbitrary magnetization field ~ M(~r) and free current density ~j(~r). We start with the magnetic force density ~ f acting on a matter element, modelled as a collection of microscopic magnetic dipoles in addition to the free currents. We show that there is a unique tensor T quadratic in...
We developed techniques to assess the utility of a nuclear magnetic resonance (NMR) indicator for cerebral blood flow studies in cats, using Freon-22 for the first candidate. A PIN-diode-switched NMR experiment allowed the acquisition of an arterial as well as a cerebral fluorine-19 signal proportional to concentration vs. time in a 1.89 T magnet. Mean +/- SD blood:brain partition coefficients ...
The field of application of magnetic resonance spectroscopy (MRS) in biomedical research is expanding all the time and providing opportunities to investigate tissue metabolism and function. The data derived can be integrated with the information on tissue structure gained from conventional and non-conventional magnetic resonance imaging (MRI) techniques. Clinical MRS is also strongly expected t...
I briefly review some aspects of the effect of magnetic fields in the high density regime relevant to neutron stars, focusing mainly on compact star structure and composition, superconductivity, combustion processes, and gamma ray bursts. THE “MAGNETIC FIELD” OF “NEUTRON STARS” A large body of evidence now identifies the presence of strong magnetic fields at (or very near) the surface of neutro...
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